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openssl/crypto/ec/ec_key.c
Dr. Stephen Henson 4b0555ec9d Add no signing flag. 
Add a flag to EC_METHOD for curves which do not support signing.
New function EC_KEY_can_sign() returns 1 is key can be used for signing.
Return an explicit error is an attempt is made to sign with
no signing curves.

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Emilia Käsper <emilia@openssl.org>
2016-02-28 22:54:53 +00:00

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/*
* Written by Nils Larsch for the OpenSSL project.
*/
/* ====================================================================
* Copyright (c) 1998-2005 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. All advertising materials mentioning features or use of this
* software must display the following acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
*
* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For written permission, please contact
* openssl-core@openssl.org.
*
* 5. Products derived from this software may not be called "OpenSSL"
* nor may "OpenSSL" appear in their names without prior written
* permission of the OpenSSL Project.
*
* 6. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
*
* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
* ====================================================================
*
* This product includes cryptographic software written by Eric Young
* (eay@cryptsoft.com). This product includes software written by Tim
* Hudson (tjh@cryptsoft.com).
*
*/
/* ====================================================================
* Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
* Portions originally developed by SUN MICROSYSTEMS, INC., and
* contributed to the OpenSSL project.
*/
#include <internal/cryptlib.h>
#include <string.h>
#include "ec_lcl.h"
#include <openssl/err.h>
#ifndef OPENSSL_NO_ENGINE
# include <openssl/engine.h>
#endif
EC_KEY *EC_KEY_new(void)
{
return EC_KEY_new_method(NULL);
}
EC_KEY *EC_KEY_new_by_curve_name(int nid)
{
EC_KEY *ret = EC_KEY_new();
if (ret == NULL)
return NULL;
ret->group = EC_GROUP_new_by_curve_name(nid);
if (ret->group == NULL) {
EC_KEY_free(ret);
return NULL;
}
if (ret->meth->set_group != NULL
&& ret->meth->set_group(ret, ret->group) == 0) {
EC_KEY_free(ret);
return NULL;
}
return ret;
}
void EC_KEY_free(EC_KEY *r)
{
int i;
if (r == NULL)
return;
i = CRYPTO_add(&r->references, -1, CRYPTO_LOCK_EC);
REF_PRINT_COUNT("EC_KEY", r);
if (i > 0)
return;
REF_ASSERT_ISNT(i < 0);
if (r->meth->finish != NULL)
r->meth->finish(r);
#ifndef OPENSSL_NO_ENGINE
ENGINE_finish(r->engine);
#endif
if (r->group && r->group->meth->keyfinish)
r->group->meth->keyfinish(r);
CRYPTO_free_ex_data(CRYPTO_EX_INDEX_EC_KEY, r, &r->ex_data);
EC_GROUP_free(r->group);
EC_POINT_free(r->pub_key);
BN_clear_free(r->priv_key);
OPENSSL_clear_free((void *)r, sizeof(EC_KEY));
}
EC_KEY *EC_KEY_copy(EC_KEY *dest, EC_KEY *src)
{
if (dest == NULL || src == NULL) {
ECerr(EC_F_EC_KEY_COPY, ERR_R_PASSED_NULL_PARAMETER);
return NULL;
}
if (src->meth != dest->meth) {
if (dest->meth->finish != NULL)
dest->meth->finish(dest);
if (dest->group && dest->group->meth->keyfinish)
dest->group->meth->keyfinish(dest);
#ifndef OPENSSL_NO_ENGINE
if (ENGINE_finish(dest->engine) == 0)
return 0;
dest->engine = NULL;
#endif
}
/* copy the parameters */
if (src->group != NULL) {
const EC_METHOD *meth = EC_GROUP_method_of(src->group);
/* clear the old group */
EC_GROUP_free(dest->group);
dest->group = EC_GROUP_new(meth);
if (dest->group == NULL)
return NULL;
if (!EC_GROUP_copy(dest->group, src->group))
return NULL;
}
/* copy the public key */
if (src->pub_key != NULL && src->group != NULL) {
EC_POINT_free(dest->pub_key);
dest->pub_key = EC_POINT_new(src->group);
if (dest->pub_key == NULL)
return NULL;
if (!EC_POINT_copy(dest->pub_key, src->pub_key))
return NULL;
}
/* copy the private key */
if (src->priv_key != NULL) {
if (dest->priv_key == NULL) {
dest->priv_key = BN_new();
if (dest->priv_key == NULL)
return NULL;
}
if (!BN_copy(dest->priv_key, src->priv_key))
return NULL;
if (src->group->meth->keycopy
&& src->group->meth->keycopy(dest, src) == 0)
return NULL;
}
/* copy the rest */
dest->enc_flag = src->enc_flag;
dest->conv_form = src->conv_form;
dest->version = src->version;
dest->flags = src->flags;
if (!CRYPTO_dup_ex_data(CRYPTO_EX_INDEX_EC_KEY,
&dest->ex_data, &src->ex_data))
return NULL;
if (src->meth != dest->meth) {
#ifndef OPENSSL_NO_ENGINE
if (src->engine != NULL && ENGINE_init(src->engine) == 0)
return NULL;
dest->engine = src->engine;
#endif
dest->meth = src->meth;
}
if (src->meth->copy != NULL && src->meth->copy(dest, src) == 0)
return NULL;
return dest;
}
EC_KEY *EC_KEY_dup(EC_KEY *ec_key)
{
EC_KEY *ret = EC_KEY_new_method(ec_key->engine);
if (ret == NULL)
return NULL;
if (EC_KEY_copy(ret, ec_key) == NULL) {
EC_KEY_free(ret);
return NULL;
}
return ret;
}
int EC_KEY_up_ref(EC_KEY *r)
{
int i = CRYPTO_add(&r->references, 1, CRYPTO_LOCK_EC);
REF_PRINT_COUNT("EC_KEY", r);
REF_ASSERT_ISNT(i < 2);
return ((i > 1) ? 1 : 0);
}
int EC_KEY_generate_key(EC_KEY *eckey)
{
if (eckey == NULL || eckey->group == NULL) {
ECerr(EC_F_EC_KEY_GENERATE_KEY, ERR_R_PASSED_NULL_PARAMETER);
return 0;
}
if (eckey->meth->keygen != NULL)
return eckey->meth->keygen(eckey);
ECerr(EC_F_EC_KEY_GENERATE_KEY, EC_R_OPERATION_NOT_SUPPORTED);
return 0;
}
int ossl_ec_key_gen(EC_KEY *eckey)
{
int ok = 0;
BN_CTX *ctx = NULL;
BIGNUM *priv_key = NULL;
const BIGNUM *order = NULL;
EC_POINT *pub_key = NULL;
if (eckey->group->meth->keygen != NULL)
return eckey->group->meth->keygen(eckey);
if ((ctx = BN_CTX_new()) == NULL)
goto err;
if (eckey->priv_key == NULL) {
priv_key = BN_new();
if (priv_key == NULL)
goto err;
} else
priv_key = eckey->priv_key;
order = EC_GROUP_get0_order(eckey->group);
if (order == NULL)
goto err;
do
if (!BN_rand_range(priv_key, order))
goto err;
while (BN_is_zero(priv_key)) ;
if (eckey->pub_key == NULL) {
pub_key = EC_POINT_new(eckey->group);
if (pub_key == NULL)
goto err;
} else
pub_key = eckey->pub_key;
if (!EC_POINT_mul(eckey->group, pub_key, priv_key, NULL, NULL, ctx))
goto err;
eckey->priv_key = priv_key;
eckey->pub_key = pub_key;
ok = 1;
err:
if (eckey->pub_key == NULL)
EC_POINT_free(pub_key);
if (eckey->priv_key != priv_key)
BN_free(priv_key);
BN_CTX_free(ctx);
return (ok);
}
int EC_KEY_check_key(const EC_KEY *eckey)
{
int ok = 0;
BN_CTX *ctx = NULL;
const BIGNUM *order = NULL;
EC_POINT *point = NULL;
if (eckey == NULL || eckey->group == NULL || eckey->pub_key == NULL) {
ECerr(EC_F_EC_KEY_CHECK_KEY, ERR_R_PASSED_NULL_PARAMETER);
return 0;
}
if (eckey->group->meth->keycheck)
return eckey->group->meth->keycheck(eckey);
if (EC_POINT_is_at_infinity(eckey->group, eckey->pub_key)) {
ECerr(EC_F_EC_KEY_CHECK_KEY, EC_R_POINT_AT_INFINITY);
goto err;
}
if ((ctx = BN_CTX_new()) == NULL)
goto err;
if ((point = EC_POINT_new(eckey->group)) == NULL)
goto err;
/* testing whether the pub_key is on the elliptic curve */
if (EC_POINT_is_on_curve(eckey->group, eckey->pub_key, ctx) <= 0) {
ECerr(EC_F_EC_KEY_CHECK_KEY, EC_R_POINT_IS_NOT_ON_CURVE);
goto err;
}
/* testing whether pub_key * order is the point at infinity */
order = eckey->group->order;
if (BN_is_zero(order)) {
ECerr(EC_F_EC_KEY_CHECK_KEY, EC_R_INVALID_GROUP_ORDER);
goto err;
}
if (!EC_POINT_mul(eckey->group, point, NULL, eckey->pub_key, order, ctx)) {
ECerr(EC_F_EC_KEY_CHECK_KEY, ERR_R_EC_LIB);
goto err;
}
if (!EC_POINT_is_at_infinity(eckey->group, point)) {
ECerr(EC_F_EC_KEY_CHECK_KEY, EC_R_WRONG_ORDER);
goto err;
}
/*
* in case the priv_key is present : check if generator * priv_key ==
* pub_key
*/
if (eckey->priv_key != NULL) {
if (BN_cmp(eckey->priv_key, order) >= 0) {
ECerr(EC_F_EC_KEY_CHECK_KEY, EC_R_WRONG_ORDER);
goto err;
}
if (!EC_POINT_mul(eckey->group, point, eckey->priv_key,
NULL, NULL, ctx)) {
ECerr(EC_F_EC_KEY_CHECK_KEY, ERR_R_EC_LIB);
goto err;
}
if (EC_POINT_cmp(eckey->group, point, eckey->pub_key, ctx) != 0) {
ECerr(EC_F_EC_KEY_CHECK_KEY, EC_R_INVALID_PRIVATE_KEY);
goto err;
}
}
ok = 1;
err:
BN_CTX_free(ctx);
EC_POINT_free(point);
return (ok);
}
int EC_KEY_set_public_key_affine_coordinates(EC_KEY *key, BIGNUM *x,
BIGNUM *y)
{
BN_CTX *ctx = NULL;
BIGNUM *tx, *ty;
EC_POINT *point = NULL;
int ok = 0;
#ifndef OPENSSL_NO_EC2M
int tmp_nid, is_char_two = 0;
#endif
if (key == NULL || key->group == NULL || x == NULL || y == NULL) {
ECerr(EC_F_EC_KEY_SET_PUBLIC_KEY_AFFINE_COORDINATES,
ERR_R_PASSED_NULL_PARAMETER);
return 0;
}
ctx = BN_CTX_new();
if (ctx == NULL)
goto err;
point = EC_POINT_new(key->group);
if (point == NULL)
goto err;
tx = BN_CTX_get(ctx);
ty = BN_CTX_get(ctx);
if (ty == NULL)
goto err;
#ifndef OPENSSL_NO_EC2M
tmp_nid = EC_METHOD_get_field_type(EC_GROUP_method_of(key->group));
if (tmp_nid == NID_X9_62_characteristic_two_field)
is_char_two = 1;
if (is_char_two) {
if (!EC_POINT_set_affine_coordinates_GF2m(key->group, point,
x, y, ctx))
goto err;
if (!EC_POINT_get_affine_coordinates_GF2m(key->group, point,
tx, ty, ctx))
goto err;
} else
#endif
{
if (!EC_POINT_set_affine_coordinates_GFp(key->group, point,
x, y, ctx))
goto err;
if (!EC_POINT_get_affine_coordinates_GFp(key->group, point,
tx, ty, ctx))
goto err;
}
/*
* Check if retrieved coordinates match originals and are less than field
* order: if not values are out of range.
*/
if (BN_cmp(x, tx) || BN_cmp(y, ty)
|| (BN_cmp(x, key->group->field) >= 0)
|| (BN_cmp(y, key->group->field) >= 0)) {
ECerr(EC_F_EC_KEY_SET_PUBLIC_KEY_AFFINE_COORDINATES,
EC_R_COORDINATES_OUT_OF_RANGE);
goto err;
}
if (!EC_KEY_set_public_key(key, point))
goto err;
if (EC_KEY_check_key(key) == 0)
goto err;
ok = 1;
err:
BN_CTX_free(ctx);
EC_POINT_free(point);
return ok;
}
const EC_GROUP *EC_KEY_get0_group(const EC_KEY *key)
{
return key->group;
}
int EC_KEY_set_group(EC_KEY *key, const EC_GROUP *group)
{
if (key->meth->set_group != NULL && key->meth->set_group(key, group) == 0)
return 0;
EC_GROUP_free(key->group);
key->group = EC_GROUP_dup(group);
return (key->group == NULL) ? 0 : 1;
}
const BIGNUM *EC_KEY_get0_private_key(const EC_KEY *key)
{
return key->priv_key;
}
int EC_KEY_set_private_key(EC_KEY *key, const BIGNUM *priv_key)
{
if (key->group == NULL || key->group->meth == NULL)
return 0;
if (key->group->meth->set_private
&& key->meth->set_private(key, priv_key) == 0)
return 0;
if (key->meth->set_private != NULL
&& key->meth->set_private(key, priv_key) == 0)
return 0;
BN_clear_free(key->priv_key);
key->priv_key = BN_dup(priv_key);
return (key->priv_key == NULL) ? 0 : 1;
}
const EC_POINT *EC_KEY_get0_public_key(const EC_KEY *key)
{
return key->pub_key;
}
int EC_KEY_set_public_key(EC_KEY *key, const EC_POINT *pub_key)
{
if (key->meth->set_public != NULL
&& key->meth->set_public(key, pub_key) == 0)
return 0;
EC_POINT_free(key->pub_key);
key->pub_key = EC_POINT_dup(pub_key, key->group);
return (key->pub_key == NULL) ? 0 : 1;
}
unsigned int EC_KEY_get_enc_flags(const EC_KEY *key)
{
return key->enc_flag;
}
void EC_KEY_set_enc_flags(EC_KEY *key, unsigned int flags)
{
key->enc_flag = flags;
}
point_conversion_form_t EC_KEY_get_conv_form(const EC_KEY *key)
{
return key->conv_form;
}
void EC_KEY_set_conv_form(EC_KEY *key, point_conversion_form_t cform)
{
key->conv_form = cform;
if (key->group != NULL)
EC_GROUP_set_point_conversion_form(key->group, cform);
}
void EC_KEY_set_asn1_flag(EC_KEY *key, int flag)
{
if (key->group != NULL)
EC_GROUP_set_asn1_flag(key->group, flag);
}
int EC_KEY_precompute_mult(EC_KEY *key, BN_CTX *ctx)
{
if (key->group == NULL)
return 0;
return EC_GROUP_precompute_mult(key->group, ctx);
}
int EC_KEY_get_flags(const EC_KEY *key)
{
return key->flags;
}
void EC_KEY_set_flags(EC_KEY *key, int flags)
{
key->flags |= flags;
}
void EC_KEY_clear_flags(EC_KEY *key, int flags)
{
key->flags &= ~flags;
}
size_t EC_KEY_key2buf(const EC_KEY *key, point_conversion_form_t form,
unsigned char **pbuf, BN_CTX *ctx)
{
if (key == NULL || key->pub_key == NULL || key->group == NULL)
return 0;
return EC_POINT_point2buf(key->group, key->pub_key, form, pbuf, ctx);
}
int EC_KEY_oct2key(EC_KEY *key, const unsigned char *buf, size_t len,
BN_CTX *ctx)
{
if (key == NULL || key->group == NULL)
return 0;
if (key->pub_key == NULL)
key->pub_key = EC_POINT_new(key->group);
if (key->pub_key == NULL)
return 0;
if (EC_POINT_oct2point(key->group, key->pub_key, buf, len, ctx) == 0)
return 0;
/*
* Save the point conversion form.
* For non-custom curves the first octet of the buffer (excluding
* the last significant bit) contains the point conversion form.
* EC_POINT_oct2point() has already performed sanity checking of
* the buffer so we know it is valid.
*/
if ((key->group->meth->flags & EC_FLAGS_CUSTOM_CURVE) == 0)
key->conv_form = (point_conversion_form_t)(buf[0] & ~0x01);
return 1;
}
size_t EC_KEY_priv2oct(const EC_KEY *eckey, unsigned char *buf, size_t len)
{
size_t buf_len;
if (eckey->group == NULL || eckey->group->meth == NULL)
return 0;
if (eckey->group->meth->priv2oct)
return eckey->group->meth->priv2oct(eckey, buf, len);
buf_len = (EC_GROUP_get_degree(eckey->group) + 7) / 8;
if (eckey->priv_key == NULL)
return 0;
if (buf == NULL)
return buf_len;
else if (len < buf_len)
return 0;
/* Octetstring may need leading zeros if BN is to short */
if (BN_bn2binpad(eckey->priv_key, buf, buf_len) == -1) {
ECerr(EC_F_EC_KEY_PRIV2OCT, EC_R_BUFFER_TOO_SMALL);
return 0;
}
return buf_len;
}
int EC_KEY_oct2priv(EC_KEY *eckey, unsigned char *buf, size_t len)
{
if (eckey->group == NULL || eckey->group->meth == NULL)
return 0;
if (eckey->group->meth->oct2priv)
return eckey->group->meth->oct2priv(eckey, buf, len);
if (eckey->priv_key == NULL)
eckey->priv_key = BN_secure_new();
if (eckey->priv_key == NULL) {
ECerr(EC_F_EC_KEY_OCT2PRIV, ERR_R_MALLOC_FAILURE);
return 0;
}
eckey->priv_key = BN_bin2bn(buf, len, eckey->priv_key);
if (eckey->priv_key == NULL) {
ECerr(EC_F_EC_KEY_OCT2PRIV, ERR_R_BN_LIB);
return 0;
}
return 1;
}
size_t EC_KEY_priv2buf(const EC_KEY *eckey, unsigned char **pbuf)
{
size_t len;
unsigned char *buf;
len = EC_KEY_priv2oct(eckey, NULL, 0);
if (len == 0)
return 0;
buf = OPENSSL_malloc(len);
if (buf == NULL)
return 0;
len = EC_KEY_priv2oct(eckey, buf, len);
if (len == 0) {
OPENSSL_free(buf);
return 0;
}
*pbuf = buf;
return len;
}
int EC_KEY_can_sign(const EC_KEY *eckey)
{
if (eckey->group == NULL || eckey->group->meth == NULL
|| (eckey->group->meth->flags & EC_FLAGS_NO_SIGN))
return 0;
return 1;
}
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